Some studies have suggested that IUDs may damage the fallopian tubes in ways that cause infertility or ectopic pregnancy. And the negative publicity surrounding the Dalkon Shield IUD in the 1970s (no longer manufactured) helped to brand the IUD with this reputation over the past three decades.

The latest evidence, however, goes a long way toward disproving the IUD-infertility link--at least in the case of IUDs made from copper, the most popular of the devices marketed today. After studying the case histories of 1800 women, researchers found no statistical correlation between IUD use and infertility--failure to conceive after 12 consecutive months of trying to achieve pregnancy.

Study Design

Researchers at a three public hospitals in Mexico City evaluated 1,311 consecutive infertile women who were admitted to determine the cause of their infertility. The study then produced an in-depth profile of the 358 women whose infertility was found to be due to tubal blockage--an important cause of infertility related to pelvic inflammatory disease (PID). Researchers compared these women with the remaining 953 infertile women who did not have tubal blockage and a second control group of 584 women who were pregnant with their first child. The investigators collected information about past contraceptive use (including copper IUDs), previous sexual relationships, and history of genital-tract infection. Each woman was also screened for antibodies to Chlamydia trachomatis to determine if she'd ever had this sexually transmitted infection.

Comparison of the 358 women who had tubal infertility with the control groups revealed that prior use of a copper IUD did not increase the risk of infertility. Tubal infertility was not associated with the length of time a copper IUD was used, the reasons for its removal, or with the presence or absence of gynecologic problems related to its use. However, researchers found that women who tested positive for antibodies to chlamydia did have a significantly higher risk of tubal infertility.

Previous studies have suggested a link between IUD use, PID, and subsequent tubal infertility, but the interpretation of data from those studies was questionable. According to the authors of the present study: "More recent studies by the World Health Organization and by a team of researchers in the United States found that the incidence of [PID] among IUD users is less than 2 episodes per 1000 years of use, consistent with conservative estimates of the incidence of [PID] in the general population."

Safe, effective, economical, reversible

The copper IUD is the safest, most effective, and most economical reversible means of contraception in the world.

Safety -- IUDs are not recommended for women who have multiple sex partners or for women whose partners are not reliably monogamous because of the risk of PID associated with sexually transmitted infection (STI). IUDs offer no protection against STIs, so IUD users who need STI protection should also use a condom. There is a small risk of PID associated with insertion of an IUD, but this only applies to the first month of use and is primarily associated with the presence of urogenital infection at the time of insertion. Properly inserted, in a good candidate with no prohibitive risk factors, IUDs are among the safest methods of birth control. Considering the risk of death associated with the many different contraceptive methods available plus the risk of death associated with pregnancy if the method fails, the only contraceptive option safer for sexually active women is for her partner to be sterilized. The ultimate test of safety for a drug or medical device is its long-term use in the general population, and copper IUDs have been used safely by millions of women around the world for more than 20 years.

Effectiveness -- The ParaGard “copper T” IUD (Ortho/McNeil) is the only copper-clad IUD available in the U.S., and it accounts for almost all IUD use in this country. The contraceptive effects of copper are not fully understood, but it is believed copper interferes with sperm transport, sperm viability, fertilization, and implantation. In the first year of use, only 8 women in a 1000 (0.8%) will become pregnant using a copper IUD, and the cumulative risk of pregnancy over 10 years of use is just 2.6%.

Economy -- Once installed, the copper IUD has a service life of 10 years, and the approximate annual cost over its 10-year service life ranges from around $20 to $50 a year, depending on the healthcare setting in which it is supplied (HMO, private practice, public clinic, etc.)

The last word

The new study in the New England Journal of Medicine was accompanied by an editorial entitled "Time to Pardon the IUD?" (Darney. NEJM. 2001;345:608-610), which concluded: "The findings reported by Hubacher et al. should reassure clinicians and women alike that copper IUDs, which are by far the most common type of IUD used in the United States and around the world, are not a threat to the health or future fertility of the women who use them, including those without children."